Back-pressure valve for drill pipes



June 24, 1930. J. R. MAHAN BACK PRESSURE VALVE FOR DRILL PIPES Filed June 11, 1928 2 Sheets Sheet 1.

June 24, 1930. I J. R. MAHAN 1,767,538

BACK PRESSURE VALVE FOR DRILL PIPES Filed June 11, 1928 ZShGQtS-Sheet 2 I lNV E NTOR Patented June 24, 1930 UNITED STATES PATENT OFFICE JOSEPH R. ,MAHAN, OF TOLEDO, OHIO, ASSIGNOIt TO THE NATIONAL SUPPLY COMPANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO I BACK-PRESSURE VALVE FOR DRILL PIPES Application filed. June 11, 1928. Serial No. 284,389.

My invention relates to back pressure sage 7, the valve head seating against the valves for drill pipes. lower end thereof adjacent to the said pas- Drill pipes are sometimes provided with sage. one or more float valves for relieving the Within the casing 1 is the large chamber 5 couplings, the derrick and other well equip- -8 bounded laterally by the wall of the cas- 55 ment from strain or injury and for proing and above by the valve head 4 and the viding safeguards against serious damage to valve seat 6 and below by'the internal anthe drill pipes and the wells in case the nular shoulder 9 and the lower annular end pipes should be accidentally dropped down of the hollow plug or member 10. The low- 1 the well. One object of this invention is to er end of the casing and the pin 3 have the so provide a valve structure which is not liable axial continuous passage 11. Between the to become clogged by material carried in shoulder 9 and the top ofthe passage 11 suspension by the fluid flowing through the the casing has the annular space 12 whose pipe. Another object is to provide a strucdiameter is greater than that of the pas- 15 ture which will prevent the valve head from sage 11. The interior wall of the space 12 e 4 interrupting the circulation of fluid in caseis threaded and receives exterior threads on the head should break off from its stem. .the lower end of the member 10. The in- Another object is to provide means whereby terior surface of the member within the the valve seat is entirely unobstructed andspace 12 is continuous or flush with the wall will not entrap or collect sand or gravel of the passage 11. 70 which has been the cause of considerable The outer surface of the member 10 from trouble in the operation of float valves. about the shoulder 9 upwardly tapers and Other objects appear hereinafter. terminates within the chamber 8 and at Referring to the accompanying drawing, some distance below the seat or bushing 6.

Fig. 1 is a central vertical section of a spe- The interior surface of the member 10 tap- 75 cial coupling containing a floating valve ers upwardly also and has inwardly proassembly made in accordance with my injecting vertical ribs 13 providing thevervention, the section being on the line 11 tical passages 14 between successive ribs. on Fig. 2. Figs. 2 and 3 are cross-sections The opposing or inner vertical edges of the of Fig. 1 on the lines 22 and 3.-3, respecribs form a guide for the valve stem-5. The so tively. Fig. 4 is a central vertical section member 10 has vertically elongated lateral showing a modified form of my invention; ports 15 extending upwardly from near the Fig. 5, a perspective of a modified hollow shoulder 9, these ports tapering upwardly plug or member; and Fig. 6, a section on to provide outlets increasing in capacity as v the line 66 on Fig. 4. the space between the casing 1 and the mem- 35 On Figs. 1 to 3, 1 designates a special holber 10 decreases. low coupling or casing, having the threaded A vertical tube 16 is screwed into the socket 2 at its upper end to which a string upper end of the member 10 and is conof drill pipe is to be attached. and at its centric therewith. It encloses the coded lower end the tapered threaded pin 3 to spring 17 which surrounds the valve stem which the drill bit is to be connected either and bears below on the upper ends of the directly or through one or more interposed ribs 13 and above against the lower side of pipe lengths. r the valve head. The tube 16 does not reach I show a valve of the mushroom type havthe valve-head when the latter 1s on its seat,

45 ing the upwardly tapering head 4 and the but forms astop for the valve head when pendent stem 5. The head seats by upward moved in its opening direction. The tube movement against the annular bushing or does not overlap the passages 14, as shown valve seat 6 which is a ring screwed into in Fig. 1. threads on the interior face of the casing \Vhen a drill string is floated into a well 1. The seat has a large uninterrupted pas hole, the valve prevents the well fluid from passing up "through the string, but opens readily when fluid is forced down through the string in a manner readily understood by. those acquainted with the well drilling art.

\Vhen fluid descends throu h the drill strin past the valve head, the atter acts as a bafie or guide to direct the sand and other coarse matter outwardly away from the tube 16. As the fluid descends through the chamber 8 most of it passes down between the casing l and the member 10 and out through the passages and down the passage 11. Some of the fluid enters the tube 16 and passes through it and the passages 14 and into the passage 11. The passage of the fluid down the tube and the passages 14 prevents the collection of sand and the like tending to prevent the action of the valv stem and the spring.

Preferably the member 10 is screwed down so as to rest on the bottom of the space 12 in order to take downward strains off from the screw-threads.

In case the valvehead should become broken off from the stem 5, it would drop down into the annular space around the member 10 and would at most clog one of the ports 15 and if it should lod e between two ports, it would not clog any 0 the ports.

Referring now to Figs. 4 to 6, the parts are the same as in Fig. 1 except as to the hollow plug or member marked 10 on Figs. 1 to 3 and 10 on Figs. 4 to 6. The plug 10 is cylindrical and its ports,15 are shown extending from their bases entirely to the top of the plug. The sides of the ports-15 are shown parallel but this is not essential. The ports have their bases at or near the lower ends of the ribs 13 whose inner edges guide the valve stem 5, so that the fluid which passes the valve head 4 must flow in contact with the sides of the ribs 13*, thereby preventing the spaces 14 between consecutive ribs becoming clog ed by the depositing of solid matter earned by the said fluid. The fluid enters the spaces between the ribs both from the sides and the top of the plug 10.

I claim- 1.- In a coupling in a drill string, a chamber, an annular valve seat at its upper end,

a valve in the chamber seating upwardlyagainst the valve seat, and a hollow member projecting upwardly within the chamber and having ports connecting the chamber to the hollow of the member, the hollow of the member being open to the interior of the drill string below the chamber, the space between the hollow member and the wall of the chamber beingv adapted to receive the valve, if broken off from its stem, without the valve blocking all the ports.

2. In a coupling in a drill string, a chama valve in the chamber seating upwardly against the valve seat, a member within the chamber, a valve stem connected to the lower side of the valve and guided by an opening in the member, a spring around the stem between the valve and the member, and a tube surroundin the spring and the stem and communicating below with passages in the said member and in communication with the said opening. 3. In a coupling in a drill string, a chamber, an annular valve seat at its upper end,

ber, an annular valve seat at its upper end,

a valve in the chamber seating upwardly against the valve seat, a spring tending to move the valve toward its seat, a valve stem attached to the under, side of the valve, a member having a guiding opening for the stem, and passages in the member and in communication with the opening connecting the chamber to the interior of the drill strin below the chamber.

5. In a'coupling in a drill string, a chamber, an annular valve seat at its upper end, a valve in the chamber seating upwardly against the valve seat, a valve stem attached to the under side of the valve, a member having a guiding opening for the stem, passages in the member and in communication with an opening connecting the chamber to the interior of the drill string below the chamber, a spring encircling the stem, tending to move the valve toward its seat, and seatedon the said member, and a tube surrounding the spring and attached to the said member, the top of the tube not reach- JOSEPH R. MAHAN.

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